Signaling for configuration of downlink coordinated multipoint communications

ABSTRACT

Embodiments of the present disclosure describe devices, methods, computer-readable media, and systems configurations for configuration of downlink coordinated multipoint (CoMP) communications in a wireless communication network. A user equipment (UE) may receive, from an evolved Node B (eNB), a radio resource control (RRC) transmission including channel state informations (CSI) reference signal (RS) parameters for a plurality of transmission points. The UE may subsequently receive a medium access control (MAC) control element (CE) including a plurality of index bits corresponding to one or more activated transmission points of the plurality of transmission points for which the feedback module is to generate CSI-RS feedback. The eNB may dynamically update the transmission points that are activated for CSI-RS feedback. The UE may receive another MAC CE from the eNB to notify the UE of the updated set of activated transmission points.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Patent Application No. 61/595,576, filed Feb. 6, 2012, entitled “ADVANCED WIRELESS

COMMUNICATION SYSTEMS AND TECHNIQUES,” the entire disclosure of which is hereby incorporated by reference.

FIELD

Embodiments of the present invention relate generally to the field of communications, and more particularly, to signaling for configuration of downlink coordinated multipoint communications.

BACKGROUND

Coordinated multipoint (CoMP) systems have been developed in order to improve various operational parameters in wireless networks. There are three types of CoMP systems: joint transmission (JT); dynamic point selection (DPS); and cooperative scheduling and cooperative beamforming (CS/CB). In JT CoMP, both a serving point, e.g., an enhanced node base station (eNB), and a coordinating point, e.g., another eNB, may send the same data to a user equipment (UE). In DPS CoMP, a transmission point may be dynamically selected among different candidates, e.g., a macro-node eNB and a pico-node eNB. In CS/CB CoMP, coordinating nodes may suppress interference of interfering channels. Effective management of CoMP communications with a UE may require definition of various CoMP sets of transmission points. However, the UE may not provide sufficient feedback to allow the eNB to effectively determine the CoMP sets.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.

FIG. 1 schematically illustrates a wireless communication network in accordance with various embodiments.

FIG. 2 is a block diagram illustrating a user equipment in accordance with various embodiments.

FIG. 3 is a block diagram illustrating a base station in accordance with various embodiments.

FIG. 4A illustrates example abstract syntax notation one (ASN.1) code for an RRC transmission in accordance with various embodiments.

FIG. 4B illustrates another example ASN.1 code for an RRC transmission in accordance with various embodiments.

FIG. 4C illustrates yet another example ASN.1 code for an RRC transmission in accordance with various embodiments.

FIG. 5 is a table showing logical channel identifiers (LCIDs) for medium access control (MAC) protocol data unit (PDU) subheaders in accordance with various embodiments.

FIG. 6 shows a body of a MAC control element (CE) including one octet in accordance with various embodiments.

FIG. 7 shows a body of a MAC CE including two octets in accordance with various embodiments.

FIG. 8 is a table showing example assigned fields of R-bits of the MAC CE body of FIG. 6, in accordance with various embodiments.

FIG. 9 is a table showing example assigned fields of R-bits of the MAC CE body of FIG. 7, in accordance with various embodiments.

FIG. 10 is a flowchart illustrating a method to support downlink coordinated multipoint (CoMP) configuration that may be performed by a user equipment in accordance with various embodiments.

FIG. 11 is a flowchart illustrating a downlink CoMP management method that may be performed by a base station in accordance with various embodiments.

FIG. 12 is a block diagram illustrating an example system in accordance with various embodiments.

DETAILED DESCRIPTION

Illustrative embodiments of the present disclosure include, but are not limited to, methods, systems, and apparatuses for configuring downlink coordinated multipoint (CoMP) communications in a wireless communication network.

Various aspects of the illustrative embodiments will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that alternate embodiments may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to one skilled in the art that alternate embodiments may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative embodiments.

Further, various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the illustrative embodiments; however, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

The phrase “in some embodiments” is used repeatedly. The phrase generally does not refer to the same embodiments; however, it may. The terms “comprising,” “having,” and “including” are synonymous, unless the context dictates otherwise. The phrase “A and/or B” means (A), (B), or (A and B). The phrase “A/B” means (A), (B), or (A and B), similar to the phrase “A and/or B”. The phrase “at least one of A, B and C” means (A), (B), (C), (A and B), (A and C), (B and C) or (A, B and C). The phrase “(A) B” means (B) or (A and B), that is, A is optional.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described, without departing from the scope of the embodiments of the present disclosure. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that the embodiments of the present disclosure be limited only by the claims and the equivalents thereof.

As used herein, the term “module” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

FIG. 1 schematically illustrates a wireless communication network 100 in accordance with various embodiments. Wireless communication network 100 (hereinafter “network 100”) may be an access network of a 3rd Generation Partnership Project (3GPP) long-term evolution (LTE) network such as evolved universal mobile telecommunication system (UMTS) terrestrial radio access network (E-UTRAN). The network 100 may include a base station, e.g., evolved Node B (eNB) 104, configured to wirelessly communicate with user equipment (UE) 108.

At least initially, the eNB 104 may have an established wireless connection with the UE 108 and may operate as a serving node for CoMP communications with the UE 108. The eNB 104 may include one or more transmission points 112 a-c that service individual cells 116 a-c of the network 100. For example, transmission point 112 a may cover a first cell 116 a, transmission point 112 b may cover a second cell 116 b, and transmission point 112 c may cover a third cell 116 c. In other embodiments, the eNB 104 may include only one transmission point and/or may only cover one cell. The network 100 may further include one or more additional transmission points 112 d-o. In some embodiments, the transmission points 112 d-o may be remote radio heads (RRHs), also referred to as remote radio equipment (RRE)) and/or base stations (e.g., eNBs). In some embodiments, the transmission points 112 d-o may transmit with a lower power than eNB 104. Transmission points 112 d-o may be located in and/or associated with cells 116 a-c as shown.

The transmission points 112 d-o may be configured to facilitate wireless communication with the UE 108 through coordination with the eNB 104. The one or more additional transmission points 112 d-o may be collectively referred to as “coordinating nodes.” In some embodiments, a transmission point may transition between coordinating and serving node roles. The serving node and coordinating nodes may communicate with one another over a wireless connection and/or a wired connection (e.g., a high-speed fiber backhaul connection).

As shown in FIG. 2, the UE 108 may include a communications module 220, a feedback module 224, and memory 228 coupled with one another at least as shown. The communications module 220 may be further coupled with one or more of a plurality of antennas 232 of the UE 108 for communicating wirelessly over network 100.

The UE 108 may include any suitable number of antennas 232. In various embodiments, the UE 108 may include at least as many antennas 232 as a number of simultaneous spatial layers or streams received by the UE 108 from the transmission points 112 a-o, although the scope of the present disclosure may not be limited in this respect. The number of simultaneous spatial layers or streams may also be referred to as transmission rank, or simply rank.

One or more of the antennas 232 may be alternately used as transmit or receive antennas. Alternatively, or additionally, one or more of the antennas 232 may be dedicated receive antennas or dedicated transmit antennas.

As shown in FIG. 3, eNB 104 may include a communications module 336 and a CoMP management module 340 coupled with one another at least as shown. The communications module 336 may be further coupled with one or more of a plurality of antennas 344 of the eNB 104. The communications module 336 may communicate with (e.g., transmit information to and/or receive information from) one or more UEs (e.g., UE 108). In various embodiments, the eNB 104 may include at least as many antennas 344 as a number of simultaneous transmission streams transmitted to the UE 108, although the scope of the present disclosure may not be limited in this respect. One or more of the antennas 344 may be alternately used as transmit or receive antennas. Alternatively, or additionally, one or more of the antennas 344 may be dedicated receive antennas or dedicated transmit antennas. Additionally, one or more of the antennas 344 may be associated with individual transmission points 112 a-c (e.g., dedicated for communications within an individual cell 116 a-c). Alternatively, or additionally, one or more of the antennas 344 may alternate between communicating in one or more cells 116 a-c.

In some embodiments, one or more of transmission points 112 d-o may have similar modules/components as eNB 104.

In various embodiments, the feedback module 224 of the UE 108 may receive a radio resource control (RRC) transmission from the eNB 104. The RRC transmission may include CoMP configuration parameters. For example, the RRC transmission may include channel state information (CSI) reference signal (RS) parameters for a plurality of transmission points (e.g., a plurality of the transmission points 112 a-o). The transmission points may be initial candidates for CoMP communications with the UE 108. These transmission points may be collectively referred to as a candidate measurement set.

In various embodiments, the UE 108 may subsequently receive a medium access control (MAC) control element (CE) that indicates one or more of the candidate transmission points that are activated for CSI-RS feedback. The activated transmission points may be collectively referred to as a CoMP Measurement Set of transmission points for which the UE 108 is to generate CSI-RS feedback. The UE 108 may generate the CSI-RS feedback for the activated transmission points based on the CSI-RS parameters, and may transmit the CSI-RS feedback for one or more of the activated transmission points to the eNB 104. In some embodiments, the CSI-RS feedback may be fast CSI-RS feedback (as opposed to long-term (average) CSI-RS feedback).

The eNB 104 may select transmission points for a cooperating set and a scheduled transmission point set from the transmission points for which the eNB 104 receives the fast CSI-RS feedback information. The cooperating set may include the transmission points that cooperate for CoMP transmissions to the UE 108. The eNB 104 may determine the transmission points included in the cooperating set based on the received CSI-RS feedback, other scheduling decisions, and/or other data/factors. The cooperating set may include one or more transmission points scheduled for transmission to the UE 108 on a physical downlink shared channel (PDSCH). Additionally, the cooperating set may include any transmission points scheduled to mute (e.g., not transmit) the PDSCH for the corresponding channel resources. The scheduled transmission points set may include only the one or more transmission points scheduled to transmit to the UE 108 on the PDSCH.

The eNB 104 may dynamically update which transmission points are included in the CoMP Measurement Set. The CoMP Measurement Set may be updated, for example, based on the received CSI-RS feedback information, other scheduling decisions, and/or other data/factors. The eNB 104 may send further MAC CEs to notify the UE 108 of the activated transmission points included in the updated CoMP Measurement Set. The UE 108 may reference the CoMP configuration parameters that were previously received in the RRC transmission. Accordingly, the eNB 104 may not need to re-send the CoMP configuration parameters. Thus, the RRC signaling and/or MAC CE may allow dynamic activation/deactivation of CSI-RS feedback in an efficient manner.

FIG. 4A illustrates example abstract syntax notation one (ASN.1) code 400 for an RRC transmission in accordance with various embodiments. The contents of the RRC transmission may be sent all at once or in separate transmissions.

As discussed above, the RRC transmission may include CoMP configuration parameters related to individual transmission points and/or cells that are candidates for CoMP transmissions to the UE 108. The CoMP configuration parameters may include CSI-RS parameters for the individual candidate transmission points. The CSI-RS parameters may include, for example, CSI-RS resource configuration parameters, zero-power CSI-RS configuration parameters, uplink control channel parameters, and/or a CSI feedback mode indicator. The CSI-RS resource configuration parameters may include, for example, a transmit power, a periodicity, a subframe offset, an initialization seed for scrambling code, a number of antenna ports, and/or an index related to the individual transmission points of the candidate measurement set. The zero-power CSI-RS configuration parameters may include conventional zero-power CSI-RS configuration parameters and/or zero-power CSI-RS configuration parameters for interference measurements.

The CSI-RS parameters may include and/or be associated with indices corresponding to individual transmission points of the candidate measurement set. The indices may be assigned explicitly, and/or implicitly (e.g., based on the order of CSI-parameters in the RRC transmission). The indices may allow the MAC CE to efficiently activate and/or deactivate the transmission points for CSI-RS feedback, as further discussed herein.

In some embodiments, CoMP configuration parameters in the RRC transmission may further include a maximum number corresponding to the maximum number of transmission points of the CoMP Measurement Set for which the UE 108 is to transmit the CSI-RS feedback. The UE 108 may select a number of the activated transmission points based on a quality of the respective transmissions (e.g., based on the generated CSI-RS feedback), wherein the number is less than or equal to the maximum number. The UE 108 may transmit the generated CSI-RS feedback for the selected transmission points to the eNB 104.

In some embodiments, the CoMP configuration parameters in the RRC transmission may further include cell-specific parameters. FIG. 4B shows one example of ASN.1 code 410 for an RRC transmission including cell-specific parameters. An alternative example ASN.1 code 420 is shown in FIG. 4C. The parameters defined by ASN.1 code 410 and/or 420 may be included in the same RRC transmission as the parameters included in ASN.1 code 400 and/or in a different transmission.

The cell-specific parameters may include, for example, frame structure parameters, such as multicast-broadcast single frequency network (MBSFN) subframe indexes within the radio frame, a number of antenna ports for common reference signals (CRSs), a CRS frequency shift (e.g., 0 to 5), a subframe shift with respect to the serving cell, a cell identifier, a number of symbols in a physical downlink control channel (PDCCH) transmitted by the cell, and/or positioning reference signal (PRS) parameters associated with individual cells (e.g., cells 116 a-c).

The cell-specific parameters may include a newCarrierType parameter to indicate if the cell is configured with a new carrier type. If multiple carrier types are defined with different treatments in CoMP, this parameter may be enumerated with multiple possible values (e.g., 1-4). For some carrier types, some of the cell-specific parameters may not be relevant or applicable. Those cell-specific parameters may or may not be included for those carrier types.

In some embodiments, the CoMP configuration parameters in the RRC transmission may further include a CSI-RS bandwidth parameter for individual transmission points of the candidate measurement set. In some embodiments, one or more of the transmission points 112 a-o may transmit with a different bandwidth than other transmission points 112 a-o. For example, higher power transmission points may have a different bandwidth than lower power transmission points. The bandwidth of the transmission point may affect some feedback measurements, such as wideband CSI measurements. Accordingly, the CSI-RS bandwidth parameter may allow the UE 108 to account for the bandwidth of the transmission point when generating feedback information.

In various embodiments, the CoMP configuration parameters received via the RRC transmission may be stored by the UE 108 (e.g., in memory 228). The feedback module 224 may retrieve the parameters from the memory 228 for the transmission points that are activated for CSI-RS feedback by the MAC CE, as further discussed herein.

In various embodiments, the MAC CE may include a MAC protocol data unit (PDU) subheader with a logical channel identifier (LCID) to identify the MAC CE as related to activation and/or deactivation of CSI feedback for CoMP configuration. FIG. 5 shows a Table 500 with example LCIDs for various MAC CEs. As shown in Table 500, the LCID for the MAC CE may be “11010” to indicate CoMP Activation/Deactivation. It will be apparent that other suitable LCIDs may be used.

The MAC CE may further include a body (also referred to as a payload). FIG. 6 shows a MAC CE with a body 600 having eight bits (e.g., one octet). The body 600 may include six index bits (e.g., C-bits C₀-C₅) and two R-bits (e.g., R₀ and R₁). FIG. 7 shows a MAC CE with a body 700 having sixteen bits (e.g., two octets). The body 700 may include twelve index bits (e.g., C-bits C₀-C₁₁) and four R-bits (e.g., R₀-R₃). Other embodiments may include any other suitable number of index bits, R-bits, and/or total bits, and may include any other suitable arrangement of bits.

In some embodiments, the individual index bits C_(i) may directly correspond to respective indices, i, of individual transmission points (e.g., individual configured CSI-RS resources of individual transmission points) of the candidate measurement set as configured by the RRC transmission. The index bit may have a first value (e.g., a logic 1) to indicate that the transmission point is active for CSI-RS feedback, and a second value (e.g., a logic 0) to indicate that the transmission point is not active for CSI-RS feedback.

Alternatively, the index bits may point to a bitmap of a pre-defined table including a plurality of bitmaps. The bitmap may indicate the activated transmission points based on the indices of the transmission points. This may allow a larger set of candidate transmission points to be configured and dynamically activated/deactivated for CSI-RS feedback. For example, the bitmap table may be used if a maximum, M, of transmission points that will be activated at the same time is less than the number of candidate transmission points. For example, if M is equal to three, the pre-defined bitmap table may include sixty-four possible 8-bit bitmaps (corresponding to eight candidate transmission points), with only one, two, or three bits set as activated (e.g., logic 1). In that case, the six index bits of the MAC CE body 600 may be used to point to one of the sixty-four possible 8-bit maps included in the pre-defined table.

The feedback module 224 of the UE 108 may receive the MAC CE. The feedback module 224 may then generate CSI-RS feedback (e.g., fast CSI-RS feedback) for the activated transmission points as indicated by the MAC CE. The feedback module 224 may then transmit the generated CSI-RS feedback for one or more of the activated transmission points to the eNB 104. As previously discussed, in some embodiments, the feedback module 224 may transmit the generated CSI-RS feedback for a number of transmission points less than or equal to a maximum number.

In various embodiments, the R-bits may include one or more CoMP-mode bits to indicate a CoMP mode to be used by the eNB 104 and/or UE 108. In some embodiments, the MAC CE may include a single CoMP-mode bit that has a first value (e.g., a logic 0) if the CoMP mode is joint transmission (JT), and a second value (e.g., a logic 1) if the CoMP mode is not joint transmission (e.g., dynamic point selection (DPS) or coordinated scheduling/coordinated beamforming (CS/CB)). Alternatively, the MAC CE may include a pair of CoMP-mode bits to indicate if the CoMP mode is JT, DPS, or CS/CB.

For example, FIG. 8 is a table 800 showing fields of the R-bits for MAC CE body 600 in accordance with one embodiment. The MAC CE body 600 may include one CoMP-mode bit (R₀) and one reserved bit (R₁). Alternatively, both R-bits of the MAC CE body 600 may be CoMP-mode bits.

FIG. 9 is a table 900 showing example fields of the R-bits for MAC CE body 700 in accordance with another embodiment. MAC CE body 700 may include two CoMP-mode bits (R₀ and R₁) and two reserved bits (R₂ and R₃). Alternatively, MAC CE body 700 may include only one CoMP-mode bit.

The UE 108 may determine a configuration of CSI-RS feedback to use based on the CoMP mode to be used. For example, in case of joint transmission as indicated by the one or more CoMP-mode bits, the UE 108 may provide CSI-RS feedback for the same set of preferred sub-bands for all CSI-RSs, provide CSI-RS feedback of the same rank for all CSI-RS resources, use the same receive processing to calculate rank indicator (RI), precoding matrix indicator (PMI), and/or channel quality indicator (CQI) reports, and/or provide inter-CSI-RS-resource feedback or CSI feedback aggregated across multiple CSI-RS resources depending on the CoMP mode. In case of coordinated scheduling and beamforming as indicated by the one or more CoMP-mode bits, the UE 108 may restrict the CSI-RS feedback the UE provides to a low rank for some CSI-RS resources.

In some embodiments, the MAC CEs having the same LCID may be used to configure feedback for uplink CoMP as well as downlink CoMP. In some such embodiments, the body 600 and/or 700 may include a bit to indicate if the MAC CE corresponds to downlink CoMP configuration or uplink CoMP configuration. For example, R₁ of MAC CE body 600 and/or R₂/R₃ of MAC CE body 700 may be used to indicate the MAC CE as related to downlink or uplink configuration.

In some embodiments, the MAC CE may further include a bit to enable an autonomous selection of a subset of activated CSI-RS resources for reporting by the UE 108. For example, R₁ of MAC CE body 600 and/or R₂/R₃ of MAC CE body 700 may be used for this purpose. In one embodiment, R₂ of MAC CE body 700 may be used for uplink/downlink indication, and R₃ may be used to enable autonomous selection. In some cases, if autonomous selection is activated, the UE 108 may generate CSI-RS feedback for all the configured transmission points in the candidate measurement set without regard to the value of the index bits. The UE 108 may then select a number of the transmission points up to a maximum number and transmit the CSI-RS feedback to the eNB 104 for the selected transmission points. The UE 108 may select the transmission points based on a quality of respective transmissions (e.g., based on the generated CSI-RS feedback). The maximum number may be received from the eNB 104 (e.g., in the RRC transmission discussed above), determined by the UE 108, and/or pre-programmed for the UE 108. The UE 108 may dynamically update the transmission points for which the UE 108 transmits CSI-RS feedback to the eNB 104.

As mentioned above, the eNB 104 may select the cooperating set of one or more transmission points from the CoMP Measurement Set (e.g., the activated transmission points). The eNB 104 may determine the transmission points included in the cooperating set based on the received CSI-RS feedback, other scheduling decisions, and/or other data/factors. The cooperating set may include one or more transmission points scheduled for transmission to the UE 108 on the PDSCH (e.g., the scheduled transmission points set) and any transmission points scheduled to mute (e.g., not transmit) on the PDSCH for the corresponding channel resources. In some embodiments, the identity of the cooperating set may not be transmitted to the UE 108, since the cooperating set may include transmission points which do not transmit to the UE 108 on the PDSCH.

In some embodiments, the eNB 104 may send a transmission to the UE 108 to notify the UE 108 of the transmission points scheduled for transmission to the UE 108 on the PDSCH (e.g., the scheduled transmission points set). The UE 108 may need to be notified of the scheduled transmission points, for example, for some CoMP schemes such as dynamic point selection. In other embodiments, the eNB 104 may not notify the UE 108 of the scheduled transmission points.

The transmission to notify the UE 108 of the scheduled transmission points may be sent on a physical channel, such as the PDCCH. In some embodiments, the transmission may use the indices configured for the transmission points in the RRC transmission to notify the UE of the scheduled transmission points. The UE 108 may use the configured CoMP configuration parameters to receive transmissions from the scheduled transmission points.

As previously discussed, the eNB 104 (e.g., the CoMP management module 340) may dynamically update the transmission points included in the CoMP Measurement Set and send another MAC CE to the UE 108 to notify the UE 108 of the updated CoMP Measurement Set. The eNB 104 may not need to re-send the CoMP configuration parameters, such as the CSI-RS parameters and/or cell-specific parameters. Rather, the UE 108 may use the previously received CoMP configuration parameters to generate the CSI-RS feedback and/or for subsequent CoMP communications.

The eNB 104 may update the transmission points included in the CoMP Measurement Set, for example, based on the CSI-RS fast feedback information reported by the UE 108 for the CoMP Measurement Set, feedback received for the candidate measurement set (e.g., CSI-RS-based radio resource management (RRM) measurements, CRS-based RRM measurements, and/or uplink SRS measurements), other scheduling decisions, and/or other data/factors. For example, if a quality of the CSI-RS feedback for one or more of the reported transmission points is below a threshold, the eNB 104 may seek to add and/or replace another transmission point to the CoMP Measurement Set. The eNB 104 may choose other transmission points to include in the CoMP Measurement Set from the transmission points included in the candidate measurement set. Additionally, the eNB 104 may remove one or more transmission points from the CoMP Measurement Set based on the CSI-RS feedback.

In some embodiments, the eNB 104 may receive ongoing (e.g., periodic) candidate feedback for the candidate measurement set, and may select and/or update the CoMP Measurement Set based on the candidate feedback. For example, the candidate feedback information may include long-term common reference signal (CRS) feedback information (e.g., CRS-based RRM measurements), uplink sounding reference signal (SRS) feedback information, and/or long-term CSI-RS feedback information (e.g., CSI-RS-based RRM measurements).

FIG. 10 illustrates a method 1000 to support downlink CoMP communications on a wireless communications network (e.g., network 100) in accordance with various embodiments. Method 1000 may be performed by a UE, such as UE 108. In some embodiments, the UE may include and/or have access to one or more computer-readable media having instructions stored thereon, that, when executed, cause the UE to perform the method 1000.

At 1004, the UE may receive, via radio resource control (RRC) signaling, CoMP configuration parameters for a plurality of transmission points that are candidates for CoMP transmission to the UE. The CoMP configuration parameters may include CSI-RS parameters for individual transmission points, cell-specific parameters for one or more cells associated with the transmission points, and/or a maximum number of transmission points for which the UE is to transmit CSI-RS feedback.

At 1008, the UE may receive a MAC CE including a plurality of index bits corresponding to one or more of the plurality of transmission points that are activated for CSI-RS feedback. The MAC CE may include a body similar to MAC CE body 600 and/or 700 discussed above.

At 1012, the UE may generate CSI-RS feedback (e.g., fast CSI-RS feedback) for CSI-RS resources of the activated transmission points based on the received CSI-RS parameters. At 1016, the UE may transmit the CSI-RS feedback for one or more of the activated transmission points to the eNB. In some embodiments, the UE may select a number of transmission points less than or equal to the maximum number for transmitting to the eNB.

In various embodiments, the UE may thereafter receive another MAC CE updating the transmission points that are activated for CSI-RS feedback. The UE may then generate the CSI-RS feedback for the activated transmission points indicated in the updated MAC CE.

FIG. 11 illustrates a method 1100 for managing downlink CoMP communications with a UE (e.g., UE 108). Method 1100 may be performed by an eNB, such as eNB 104. In some embodiments, the eNB may include and/or have access to one or more computer-readable media having instructions stored thereon, that, when executed, cause the UE to perform the method 1100.

At 1104, the eNB may transmit, via RRC signaling, CoMP configuration parameters for a plurality of transmission points that are candidates for CoMP transmission to the UE. The CoMP configuration parameters may include CSI-RS parameters for individual transmission points, cell-specific parameters for one or more cells associated with the transmission points, and/or a maximum number of transmission points for which the UE is to transmit CSI-RS feedback.

At 1108, the eNB may transmit a MAC CE including a plurality of index bits corresponding to one or more of the candidate transmission points that are activated for CSI-RS feedback. The MAC CE may include a body similar to MAC CE body 600 and/or 700 discussed above.

At 1112, the eNB may receive CSI-RS feedback (e.g., fast CSI-RS feedback) for one or more of the activated transmission points. The eNB may select a cooperating set of transmission points based on the received CSI-RS feedback. The cooperating set may include one or more transmission points that are scheduled to transmit on the PDSCH to the UE.

In various embodiments, the eNB may update the activated transmission points and send another MAC CE to the UE.

The eNB 104, UE 108, and/or transmission points 112 a-o described herein may be implemented into a system using any suitable hardware and/or software to configure as desired. FIG. 12 illustrates, for one embodiment, an example system 1200 comprising one or more processor(s) 1204, system control logic 1208 coupled with at least one of the processor(s) 1204, system memory 1212 coupled with system control logic 1208, non-volatile memory (NVM)/storage 1216 coupled with system control logic 1208, a network interface 1220 coupled with system control logic 1208, and input/output (I/O) devices 1232 coupled with system control logic 1208.

The processor(s) 1204 may include one or more single-core or multi-core processors. The processor(s) 1204 may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, baseband processors, etc.).

System control logic 1208 for one embodiment may include any suitable interface controllers to provide for any suitable interface to at least one of the processor(s) 1204 and/or to any suitable device or component in communication with system control logic 1208.

System control logic 1208 for one embodiment may include one or more memory controller(s) to provide an interface to system memory 1212. System memory 1212 may be used to load and store data and/or instructions, for example, for system 1200. System memory 1212 for one embodiment may include any suitable volatile memory, such as suitable dynamic random access memory (DRAM), for example.

NVM/storage 1216 may include one or more tangible, non-transitory computer-readable media used to store data and/or instructions, for example. NVM/storage 1216 may include any suitable non-volatile memory, such as flash memory, for example, and/or may include any suitable non-volatile storage device(s), such as one or more hard disk drive(s) (HDD(s)), one or more compact disk (CD) drive(s), and/or one or more digital versatile disk (DVD) drive(s), for example.

The NVM/storage 1216 may include a storage resource physically part of a device on which the system 1200 is installed or it may be accessible by, but not necessarily a part of, the device. For example, the NVM/storage 1216 may be accessed over a network via the network interface 1220 and/or over Input/Output (I/O) devices 1232.

Network interface 1220 may have a transceiver 1222 to provide a radio interface for system 1200 to communicate over one or more network(s) and/or with any other suitable device. The transceiver 1222 may implement communications module 220 of UE 108 or communications module 336 of eNB 104. In various embodiments, the transceiver 1222 may be integrated with other components of system 1200. For example, the transceiver 1222 may include a processor of the processor(s) 1204, memory of the system memory 1212, and NVM/Storage of NVM/Storage 1216. Network interface 1220 may include any suitable hardware and/or firmware. Network interface 1220 may include a plurality of antennas to provide a multiple input, multiple output radio interface. Network interface 1220 for one embodiment may include, for example, a wired network adapter, a wireless network adapter, a telephone modem, and/or a wireless modem.

For one embodiment, at least one of the processor(s) 1204 may be packaged together with logic for one or more controller(s) of system control logic 1208. For one embodiment, at least one of the processor(s) 1204 may be packaged together with logic for one or more controllers of system control logic 1208 to form a System in Package (SiP). For one embodiment, at least one of the processor(s) 1204 may be integrated on the same die with logic for one or more controller(s) of system control logic 1208. For one embodiment, at least one of the processor(s) 1204 may be integrated on the same die with logic for one or more controller(s) of system control logic 1208 to form a System on Chip (SoC).

In various embodiments, the I/O devices 1232 may include user interfaces designed to enable user interaction with the system 1200, peripheral component interfaces designed to enable peripheral component interaction with the system 1200, and/or sensors designed to determine environmental conditions and/or location information related to the system 1200.

In various embodiments, the user interfaces could include, but are not limited to, a display (e.g., a liquid crystal display, a touch screen display, etc.), a speaker, a microphone, one or more cameras (e.g., a still camera and/or a video camera), a flashlight (e.g., a light emitting diode flash), and a keyboard.

In various embodiments, the peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface.

In various embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the network interface 1220 to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite.

In various embodiments, the system 1200 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, a smartphone, etc. In various embodiments, system 1200 may have more or less components, and/or different architectures.

Although certain embodiments have been illustrated and described herein for purposes of description, a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments described herein be limited only by the claims and the equivalents thereof. 

1-53. (canceled)
 54. An apparatus to be employed by a user equipment (UE), the apparatus comprising: a communications module configured to communicate with an evolved NodeB (eNB) over a wireless communications network; a feedback module coupled to the communications module and configured to: receive a radio resource control (RRC) transmission including channel state information (CSI) reference signal (RS) parameters for a plurality of transmission points; and receive a medium access control (MAC) control element (CE) including a plurality of index bits corresponding to one or more activated transmission points of the plurality of transmission points for which the feedback module is to generate CSI-RS feedback.
 55. The apparatus of claim 54, wherein the feedback module is further configured to: generate CSI-RS feedback for the activated transmission points based on the CSI-RS parameters; and transmit the CSI-RS feedback for one or more of the activated transmission points to the eNB.
 56. The apparatus of claim 55, wherein the RRC transmission further includes a maximum number, and wherein the feedback module is further configured to: select a number of the activated transmission points based on quality of respective transmissions, wherein the number is less than or equal to the maximum number; and transmit the CSI-RS feedback for the selected transmission points.
 57. The apparatus of claim 54, wherein the CSI-RS parameters include a CSI-RS bandwidth parameter for the individual transmission points.
 58. The apparatus of claim 54, wherein the RRC transmission further includes cell-specific frame structure parameters for one or more cells to which the individual transmission points belong.
 59. The apparatus of claim 54, wherein the MAC CE includes: a MAC protocol data unit (PDU) subheader with a logical channel identifier (LCID) to identify the MAC CE as related to activation or deactivation of CSI feedback for CoMP configuration; and a body including the plurality of index bits.
 60. The apparatus of claim 54, wherein individual index bits correspond to individual CSI-RS resources of the transmission points to indicate if the CSI-RS resources are active for CSI feedback.
 61. The apparatus of claim 54, wherein the index bits point to a bitmap of a pre-defined table including a plurality of bitmaps, the bitmap indicating the activated transmission points.
 62. The apparatus of claim 54, wherein the MAC CE further includes one or more CoMP-mode bits indicating a CoMP mode to be used by the UE.
 63. The apparatus of claim 62, wherein the MAC CE includes six index bits and one CoMP-mode bit.
 64. The apparatus of claim 62, wherein the MAC CE includes twelve index bits, two CoMP-mode bits, one bit to indicate if the MAC CE corresponds to a downlink configuration or an uplink configuration, and one bit to enable an autonomous selection of a subset of activated CSI-RS resources for reporting by the UE.
 65. An apparatus for managing coordinated multipoint (CoMP) communications with a user equipment on a wireless communications network, the apparatus comprising: a communications module configured to communicate with the UE over the wireless communications network; a CoMP management module coupled to the communications module and configured to: transmit CoMP configuration parameters to the UE, the CoMP configuration parameters including channel state information (CSI) reference signal (RS) parameters for individual transmission points of a candidate measurement set including a plurality of transmission points, the CSI-RS parameters including a CSI-RS bandwidth parameter; and transmit a transmission to the UE to identify individual transmission points of the candidate measurement set for which the UE is to generate CSI-RS feedback based on the CSI-RS bandwidth parameter.
 66. The apparatus of claim 65, wherein the transmission identifying the individual transmission points for which the UE is to generate CSI feedback includes a medium access control (MAC) control element (CE) having a plurality of index bits corresponding to one or more activated transmission points of the candidate measurement set for which the UE is to generate the CSI-RS feedback.
 67. The apparatus of claim 66, wherein individual index bits correspond to individual transmission points of the candidate measurement set to indicate if a CSI-RS resource of the individual transmission point is active for CSI feedback.
 68. The apparatus of claim 66, wherein the index bits point to a bitmap of a pre-defined table including a plurality of bitmaps.
 69. The apparatus of claim 66, wherein the MAC CE further includes a CoMP-mode bit having a first value if a CoMP mode to be used by the UE is joint transmission.
 70. The apparatus of claim 66, wherein the MAC CE further includes a pair of CoMP-mode bits to indicate if a CoMP mode to be used by the UE is joint transmission, dynamic point selection, or coordinated scheduling/coordinated beamforming.
 71. The apparatus of claim 66, wherein the MAC CE includes a first bit to indicate if the MAC CE corresponds to a downlink configuration or an uplink configuration.
 72. One or more non-transitory computer-readable media having instructions, stored thereon, that, when executed cause a user equipment (UE) to: receive, via radio resource control (RRC) signaling, channel state information (CSI) reference signal (RS) parameters for a plurality of transmission points; and receive a medium access control (MAC) control element (CE) to identify one or more activated transmission points, of the plurality of transmission points, for which the UE is to generate CSI-RS feedback.
 73. The one or more computer-readable media of claim 72, wherein the instructions, when executed, further cause the UE to: generate CSI-RS feedback for the activated transmission points based on the received CSI-RS parameters; and transmit the CSI-RS feedback for one or more of the activated transmission points to the eNB.
 74. The one or more computer-readable media of claim 72, wherein the MAC CE includes a plurality of index bits, wherein individual index bits correspond to individual transmission points of the CoMP Measurement Set to indicate if the individual transmission point is active for CSI feedback.
 75. The one or more computer-readable media of claim 72, wherein the MAC CE includes a plurality of index bits, wherein the index bits point to a bitmap of a pre-defined table including a plurality of bitmaps, the bitmap indicating the activated transmission points.
 76. The one or more computer-readable media of claim 72, wherein the MAC CE further indicates a CoMP mode to be used by the UE.
 77. A method to manage coordinated multi-point (CoMP) communications with a user equipment (UE) on a wireless communications network comprising: transmitting, to the UE via radio resource control (RRC) signaling, channel state information (CSI) reference signal (RS) parameters for a plurality of transmission points; and transmitting, to the UE, a medium access control (MAC) control element (CE) including a plurality of index bits that point to a bitmap of a pre-defined table including a plurality of bitmaps, the bitmap indicating one or more activated transmission points of the plurality of transmission points for which the UE is to generate CSI-RS feedback.
 78. The method of claim 77, wherein individual bits of the bitmap correspond to individual transmission points of the CoMP Measurement Set to indicate if the individual transmission point is active for CSI feedback. 